I have also got an email from bitmain which is celebrating their birthday. The email also states that if i cannot see the coupons in my coupons tab on my account, i need to send them an email in a specified format and they will send me the coupons. Long story short, these coupons are free and even if i have not purchased a single piece of equipment from them, they are still offering me this deal.
IMO if they are not offering this deal to people who just sign up now, then it makes sense for OP to charge for these coupons and we should not chew his head off!
If they are offering the same deal to new registrants then it will be easier for people to just go ahead and create and account an get the deal! This is the way to go imo for new registrants